itkExpectationMaximizationMixtureModelEstimator.h

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/*=========================================================================
 *
 *  Copyright NumFOCUS
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         https://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/
#ifndef itkExpectationMaximizationMixtureModelEstimator_h
#define itkExpectationMaximizationMixtureModelEstimator_h
 
#include "ITKStatisticsExport.h"
#include "itkMixtureModelComponentBase.h"
#include "itkGaussianMembershipFunction.h"
#include "itkSimpleDataObjectDecorator.h"
 
namespace itk::Statistics
{
class ExpectationMaximizationMixtureModelEstimatorEnums
{
public:
  enum class TERMINATION_CODE : uint8_t
  {
    CONVERGED = 0,
    NOT_CONVERGED = 1
  };
};
// Define how to print enumeration
extern ITKStatistics_EXPORT std::ostream &
operator<<(std::ostream & out, const ExpectationMaximizationMixtureModelEstimatorEnums::TERMINATION_CODE value);

template <typename TSample>
class ITK_TEMPLATE_EXPORT ExpectationMaximizationMixtureModelEstimator : public Object
{
public:
  using Self = ExpectationMaximizationMixtureModelEstimator;
  using Superclass = Object;
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;

  itkOverrideGetNameOfClassMacro(ExpectationMaximizationMixtureModelEstimator);
  itkNewMacro(Self);
  using SampleType = TSample;
  using MeasurementType = typename TSample::MeasurementType;
  using MeasurementVectorType = typename TSample::MeasurementVectorType;

  using GaussianMembershipFunctionType = GaussianMembershipFunction<MeasurementVectorType>;
 
  using GaussianMembershipFunctionPointer = typename GaussianMembershipFunctionType::Pointer;
 
  using MembershipFunctionType = MembershipFunctionBase<MeasurementVectorType>;
  using MembershipFunctionPointer = typename MembershipFunctionType::ConstPointer;
  using MembershipFunctionVectorType = std::vector<MembershipFunctionPointer>;
  using MembershipFunctionVectorObjectType = SimpleDataObjectDecorator<MembershipFunctionVectorType>;
  using MembershipFunctionVectorObjectPointer = typename MembershipFunctionVectorObjectType::Pointer;

  using ComponentType = MixtureModelComponentBase<TSample>;

  using ComponentVectorType = std::vector<ComponentType *>;

  using ComponentMembershipFunctionType = MembershipFunctionBase<MeasurementVectorType>;

  using ProportionVectorType = Array<double>;

  void
  SetSample(const TSample * sample);

  const TSample *
  GetSample() const;

  void
  SetInitialProportions(ProportionVectorType & proportions);
 
  const ProportionVectorType &
  GetInitialProportions() const;

  const ProportionVectorType &
  GetProportions() const;

  using MembershipFunctionsWeightsArrayObjectType = SimpleDataObjectDecorator<ProportionVectorType>;
  using MembershipFunctionsWeightsArrayPointer = typename MembershipFunctionsWeightsArrayObjectType::Pointer;

  const MembershipFunctionsWeightsArrayObjectType *
  GetMembershipFunctionsWeightsArray() const;

  void
  SetMaximumIteration(int numberOfIterations);
 
  int
  GetMaximumIteration() const;

  int
  GetCurrentIteration()
  {
    return m_CurrentIteration;
  }

  int
  AddComponent(ComponentType * component);

  unsigned int
  GetNumberOfComponents() const;

  void
  Update();
 
  using TERMINATION_CODE_ENUM = ExpectationMaximizationMixtureModelEstimatorEnums::TERMINATION_CODE;
#if !defined(ITK_LEGACY_REMOVE)
  static constexpr TERMINATION_CODE_ENUM CONVERGED = TERMINATION_CODE_ENUM::CONVERGED;
  static constexpr TERMINATION_CODE_ENUM NOT_CONVERGED = TERMINATION_CODE_ENUM::NOT_CONVERGED;
#endif

  TERMINATION_CODE_ENUM
  GetTerminationCode() const;

  ComponentMembershipFunctionType *
  GetComponentMembershipFunction(int componentIndex) const;

  const MembershipFunctionVectorObjectType *
  GetOutput() const;
 
protected:
  ExpectationMaximizationMixtureModelEstimator();
  ~ExpectationMaximizationMixtureModelEstimator() override = default;
  void
  PrintSelf(std::ostream & os, Indent indent) const override;
 
  bool
  CalculateDensities();
 
  double
  CalculateExpectation() const;
 
  bool
  UpdateComponentParameters();
 
  bool
  UpdateProportions();

  void
  GenerateData();
 
private:
  const TSample * m_Sample{};
 
  int m_MaxIteration{ 100 };
  int m_CurrentIteration{ 0 };
 
  TERMINATION_CODE_ENUM m_TerminationCode{ TERMINATION_CODE_ENUM::NOT_CONVERGED };
  ComponentVectorType   m_ComponentVector{};
  ProportionVectorType  m_InitialProportions{};
  ProportionVectorType  m_Proportions{};
 
  MembershipFunctionVectorObjectPointer  m_MembershipFunctionsObject{};
  MembershipFunctionsWeightsArrayPointer m_MembershipFunctionsWeightArrayObject{};
}; // end of class
} // namespace itk::Statistics
 
#ifndef ITK_MANUAL_INSTANTIATION
#  include "itkExpectationMaximizationMixtureModelEstimator.hxx"
#endif
 
#endif